i just crash landed at sfo. tail ripped off. everyone seems fine. i'm okay. surreal. witnesses shocked that anyone could survive. >> just pancaked immediately. and then just kept sliding and sliding and sliding. it finally stopped and you could see how the fuselage kept buckling. surprised it didn't come apart all together. and it was unreal. >> reporter: helicopter pictures show the trail of destruction. impact on the stone embankment, one set of plan beilanding gear plane stabilizers, the tip of the tail, debris littering the runway. officials say there was no sign of trouble before the plane crashed. . the weather ideal, a clear day. all traffic using visual flight rules to land. pilots say landing at san francisco international can be tricky. this shows the final approach. the runway starting at the water's edge. two things they're looking at are the engines. asiana airlines saying both were in fine working order, but passengers did say they felt them add power to them just before that impact. also that left engine seems to have disappeared. and the instrument lan